/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_cfft_radix2_q15.c
 * Description:  Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

void arm_radix2_butterfly_q15(
	q15_t *pSrc,
	uint32_t fftLen,
	const q15_t *pCoef,
	uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_q15(
	q15_t *pSrc,
	uint32_t fftLen,
	const q15_t *pCoef,
	uint16_t twidCoefModifier);

void arm_bitreversal_q15(
	q15_t *pSrc,
	uint32_t fftLen,
	uint16_t bitRevFactor,
	const uint16_t *pBitRevTab);

/**
  @ingroup groupTransforms
 */

/**
  @addtogroup ComplexFFT
  @{
 */

/**
  @brief         Processing function for the fixed-point CFFT/CIFFT.
  @deprecated    Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed in the future.
  @param[in]     S    points to an instance of the fixed-point CFFT/CIFFT structure
  @param[in,out] pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place
  @return        none
 */

void arm_cfft_radix2_q15(
	const arm_cfft_radix2_instance_q15 *S,
	q15_t *pSrc)
{

	if (S->ifftFlag == 1U) {
		arm_radix2_butterfly_inverse_q15(pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier);
	} else {
		arm_radix2_butterfly_q15(pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier);
	}

	arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
}

/**
  @} end of ComplexFFT group
 */

void arm_radix2_butterfly_q15(
	q15_t *pSrc,
	uint32_t fftLen,
	const q15_t *pCoef,
	uint16_t twidCoefModifier)
{
#if defined (ARM_MATH_DSP)

	uint32_t i, j, k, l;
	uint32_t n1, n2, ia;
	q15_t in;
	q31_t T, S, R;
	q31_t coeff, out1, out2;

	//N = fftLen;
	n2 = fftLen;

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	// loop for groups
	for (i = 0; i < n2; i++) {
		coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

		ia = ia + twidCoefModifier;

		l = i + n2;

		T = read_q15x2(pSrc + (2 * i));
		in = ((int16_t)(T & 0xFFFF)) >> 1;
		T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		S = read_q15x2(pSrc + (2 * l));
		in = ((int16_t)(S & 0xFFFF)) >> 1;
		S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		R = __QSUB16(T, S);

		write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
		out1 = __SMUAD(coeff, R) >> 16;
		out2 = __SMUSDX(coeff, R);
#else
		out1 = __SMUSDX(R, coeff) >> 16U;
		out2 = __SMUAD(coeff, R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

		write_q15x2(pSrc + (2U * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

		coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

		ia = ia + twidCoefModifier;

		/* loop for butterfly */
		i++;
		l++;

		T = read_q15x2(pSrc + (2 * i));
		in = ((int16_t)(T & 0xFFFF)) >> 1;
		T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		S = read_q15x2(pSrc + (2 * l));
		in = ((int16_t)(S & 0xFFFF)) >> 1;
		S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		R = __QSUB16(T, S);

		write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
		out1 = __SMUAD(coeff, R) >> 16;
		out2 = __SMUSDX(coeff, R);
#else

		out1 = __SMUSDX(R, coeff) >> 16U;
		out2 = __SMUAD(coeff, R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

		write_q15x2(pSrc + (2U * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

	} /* groups loop end */

	twidCoefModifier = twidCoefModifier << 1U;

	/* loop for stage */
	for (k = fftLen / 2; k > 2; k = k >> 1) {
		n1 = n2;
		n2 = n2 >> 1;
		ia = 0;

		/* loop for groups */
		for (j = 0; j < n2; j++) {
			coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

			ia = ia + twidCoefModifier;

			/* loop for butterfly */
			for (i = j; i < fftLen; i += n1) {
				l = i + n2;

				T = read_q15x2(pSrc + (2 * i));

				S = read_q15x2(pSrc + (2 * l));

				R = __QSUB16(T, S);

				write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
				out1 = __SMUAD(coeff, R) >> 16;
				out2 = __SMUSDX(coeff, R);
#else
				out1 = __SMUSDX(R, coeff) >> 16U;
				out2 = __SMUAD(coeff, R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

				write_q15x2(pSrc + (2U * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

				i += n1;

				l = i + n2;

				T = read_q15x2(pSrc + (2 * i));

				S = read_q15x2(pSrc + (2 * l));

				R = __QSUB16(T, S);

				write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
				out1 = __SMUAD(coeff, R) >> 16;
				out2 = __SMUSDX(coeff, R);
#else
				out1 = __SMUSDX(R, coeff) >> 16U;
				out2 = __SMUAD(coeff, R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

				write_q15x2(pSrc + (2U * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

			} /* butterfly loop end */

		} /* groups loop end */

		twidCoefModifier = twidCoefModifier << 1U;
	} /* stages loop end */

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

	ia = ia + twidCoefModifier;

	/* loop for butterfly */
	for (i = 0; i < fftLen; i += n1) {
		l = i + n2;

		T = read_q15x2(pSrc + (2 * i));

		S = read_q15x2(pSrc + (2 * l));

		R = __QSUB16(T, S);

		write_q15x2(pSrc + (2 * i), __QADD16(T, S));

		write_q15x2(pSrc + (2 * l), R);

		i += n1;
		l = i + n2;

		T = read_q15x2(pSrc + (2 * i));

		S = read_q15x2(pSrc + (2 * l));

		R = __QSUB16(T, S);

		write_q15x2(pSrc + (2 * i), __QADD16(T, S));

		write_q15x2(pSrc + (2 * l), R);

	} /* groups loop end */


#else /* #if defined (ARM_MATH_DSP) */

	uint32_t i, j, k, l;
	uint32_t n1, n2, ia;
	q15_t xt, yt, cosVal, sinVal;


	// N = fftLen;
	n2 = fftLen;

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	/* loop for groups */
	for (j = 0; j < n2; j++) {
		cosVal = pCoef[(ia * 2)];
		sinVal = pCoef[(ia * 2) + 1];
		ia = ia + twidCoefModifier;

		/* loop for butterfly */
		for (i = j; i < fftLen; i += n1) {
			l = i + n2;
			xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
			pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;

			yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
			pSrc[2 * i + 1] = ((pSrc[2 * l + 1] >> 1U) +
							   (pSrc[2 * i + 1] >> 1U)) >> 1U;

			pSrc[2 * l] = (((int16_t)(((q31_t) xt * cosVal) >> 16)) +
						   ((int16_t)(((q31_t) yt * sinVal) >> 16)));

			pSrc[2U * l + 1] = (((int16_t)(((q31_t) yt * cosVal) >> 16)) -
								((int16_t)(((q31_t) xt * sinVal) >> 16)));

		} /* butterfly loop end */

	} /* groups loop end */

	twidCoefModifier = twidCoefModifier << 1U;

	/* loop for stage */
	for (k = fftLen / 2; k > 2; k = k >> 1) {
		n1 = n2;
		n2 = n2 >> 1;
		ia = 0;

		/* loop for groups */
		for (j = 0; j < n2; j++) {
			cosVal = pCoef[ia * 2];
			sinVal = pCoef[(ia * 2) + 1];
			ia = ia + twidCoefModifier;

			/* loop for butterfly */
			for (i = j; i < fftLen; i += n1) {
				l = i + n2;
				xt = pSrc[2 * i] - pSrc[2 * l];
				pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;

				yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
				pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;

				pSrc[2 * l] = (((int16_t)(((q31_t) xt * cosVal) >> 16)) +
							   ((int16_t)(((q31_t) yt * sinVal) >> 16)));

				pSrc[2U * l + 1] = (((int16_t)(((q31_t) yt * cosVal) >> 16)) -
									((int16_t)(((q31_t) xt * sinVal) >> 16)));

			} /* butterfly loop end */

		} /* groups loop end */

		twidCoefModifier = twidCoefModifier << 1U;
	} /* stages loop end */

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	/* loop for groups */
	for (j = 0; j < n2; j++) {
		cosVal = pCoef[ia * 2];
		sinVal = pCoef[(ia * 2) + 1];

		ia = ia + twidCoefModifier;

		/* loop for butterfly */
		for (i = j; i < fftLen; i += n1) {
			l = i + n2;
			xt = pSrc[2 * i] - pSrc[2 * l];
			pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

			yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
			pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

			pSrc[2 * l] = xt;

			pSrc[2 * l + 1] = yt;

		} /* butterfly loop end */

	} /* groups loop end */

	twidCoefModifier = twidCoefModifier << 1U;

#endif /* #if defined (ARM_MATH_DSP) */

}


void arm_radix2_butterfly_inverse_q15(
	q15_t *pSrc,
	uint32_t fftLen,
	const q15_t *pCoef,
	uint16_t twidCoefModifier)
{
#if defined (ARM_MATH_DSP)

	uint32_t i, j, k, l;
	uint32_t n1, n2, ia;
	q15_t in;
	q31_t T, S, R;
	q31_t coeff, out1, out2;

	// N = fftLen;
	n2 = fftLen;

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	/* loop for groups */
	for (i = 0; i < n2; i++) {
		coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

		ia = ia + twidCoefModifier;

		l = i + n2;

		T = read_q15x2(pSrc + (2 * i));
		in = ((int16_t)(T & 0xFFFF)) >> 1;
		T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		S = read_q15x2(pSrc + (2 * l));
		in = ((int16_t)(S & 0xFFFF)) >> 1;
		S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		R = __QSUB16(T, S);

		write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
		out1 = __SMUSD(coeff, R) >> 16;
		out2 = __SMUADX(coeff, R);
#else
		out1 = __SMUADX(R, coeff) >> 16U;
		out2 = __SMUSD(__QSUB(0, coeff), R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

		write_q15x2(pSrc + (2 * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

		coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

		ia = ia + twidCoefModifier;

		/* loop for butterfly */
		i++;
		l++;

		T = read_q15x2(pSrc + (2 * i));
		in = ((int16_t)(T & 0xFFFF)) >> 1;
		T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		S = read_q15x2(pSrc + (2 * l));
		in = ((int16_t)(S & 0xFFFF)) >> 1;
		S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

		R = __QSUB16(T, S);

		write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
		out1 = __SMUSD(coeff, R) >> 16;
		out2 = __SMUADX(coeff, R);
#else
		out1 = __SMUADX(R, coeff) >> 16U;
		out2 = __SMUSD(__QSUB(0, coeff), R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

		write_q15x2(pSrc + (2 * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

	} /* groups loop end */

	twidCoefModifier = twidCoefModifier << 1U;

	/* loop for stage */
	for (k = fftLen / 2; k > 2; k = k >> 1) {
		n1 = n2;
		n2 = n2 >> 1;
		ia = 0;

		/* loop for groups */
		for (j = 0; j < n2; j++) {
			coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

			ia = ia + twidCoefModifier;

			/* loop for butterfly */
			for (i = j; i < fftLen; i += n1) {
				l = i + n2;

				T = read_q15x2(pSrc + (2 * i));

				S = read_q15x2(pSrc + (2 * l));

				R = __QSUB16(T, S);

				write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
				out1 = __SMUSD(coeff, R) >> 16;
				out2 = __SMUADX(coeff, R);
#else
				out1 = __SMUADX(R, coeff) >> 16U;
				out2 = __SMUSD(__QSUB(0, coeff), R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

				write_q15x2(pSrc + (2 * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

				i += n1;

				l = i + n2;

				T = read_q15x2(pSrc + (2 * i));

				S = read_q15x2(pSrc + (2 * l));

				R = __QSUB16(T, S);

				write_q15x2(pSrc + (2 * i), __SHADD16(T, S));

#ifndef ARM_MATH_BIG_ENDIAN
				out1 = __SMUSD(coeff, R) >> 16;
				out2 = __SMUADX(coeff, R);
#else
				out1 = __SMUADX(R, coeff) >> 16U;
				out2 = __SMUSD(__QSUB(0, coeff), R);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

				write_q15x2(pSrc + (2 * l), (q31_t)((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF));

			} /* butterfly loop end */

		} /* groups loop end */

		twidCoefModifier = twidCoefModifier << 1U;
	} /* stages loop end */

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	/* loop for groups */
	for (j = 0; j < n2; j++) {
		coeff = read_q15x2((q15_t *)pCoef + (ia * 2U));

		ia = ia + twidCoefModifier;

		/* loop for butterfly */
		for (i = j; i < fftLen; i += n1) {
			l = i + n2;

			T = read_q15x2(pSrc + (2 * i));

			S = read_q15x2(pSrc + (2 * l));

			R = __QSUB16(T, S);

			write_q15x2(pSrc + (2 * i), __QADD16(T, S));

			write_q15x2(pSrc + (2 * l), R);

		} /* butterfly loop end */

	} /* groups loop end */

	twidCoefModifier = twidCoefModifier << 1U;

#else /* #if defined (ARM_MATH_DSP) */

	uint32_t i, j, k, l;
	uint32_t n1, n2, ia;
	q15_t xt, yt, cosVal, sinVal;

	// N = fftLen;
	n2 = fftLen;

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	/* loop for groups */
	for (j = 0; j < n2; j++) {
		cosVal = pCoef[(ia * 2)];
		sinVal = pCoef[(ia * 2) + 1];
		ia = ia + twidCoefModifier;

		/* loop for butterfly */
		for (i = j; i < fftLen; i += n1) {
			l = i + n2;
			xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
			pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;

			yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
			pSrc[2 * i + 1] = ((pSrc[2 * l + 1] >> 1U) +
							   (pSrc[2 * i + 1] >> 1U)) >> 1U;

			pSrc[2 * l] = (((int16_t)(((q31_t) xt * cosVal) >> 16)) -
						   ((int16_t)(((q31_t) yt * sinVal) >> 16)));

			pSrc[2 * l + 1] = (((int16_t)(((q31_t) yt * cosVal) >> 16)) +
							   ((int16_t)(((q31_t) xt * sinVal) >> 16)));

		} /* butterfly loop end */

	} /* groups loop end */

	twidCoefModifier = twidCoefModifier << 1U;

	/* loop for stage */
	for (k = fftLen / 2; k > 2; k = k >> 1) {
		n1 = n2;
		n2 = n2 >> 1;
		ia = 0;

		/* loop for groups */
		for (j = 0; j < n2; j++) {
			cosVal = pCoef[(ia * 2)];
			sinVal = pCoef[(ia * 2) + 1];
			ia = ia + twidCoefModifier;

			/* loop for butterfly */
			for (i = j; i < fftLen; i += n1) {
				l = i + n2;
				xt = pSrc[2 * i] - pSrc[2 * l];
				pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;

				yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
				pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;

				pSrc[2 * l] = (((int16_t)(((q31_t) xt * cosVal) >> 16)) -
							   ((int16_t)(((q31_t) yt * sinVal) >> 16)));

				pSrc[2 * l + 1] = (((int16_t)(((q31_t) yt * cosVal) >> 16)) +
								   ((int16_t)(((q31_t) xt * sinVal) >> 16)));

			} /* butterfly loop end */

		} /* groups loop end */

		twidCoefModifier = twidCoefModifier << 1U;
	} /* stages loop end */

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	cosVal = pCoef[(ia * 2)];
	sinVal = pCoef[(ia * 2) + 1];

	ia = ia + twidCoefModifier;

	/* loop for butterfly */
	for (i = 0; i < fftLen; i += n1) {
		l = i + n2;
		xt = pSrc[2 * i] - pSrc[2 * l];
		pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

		yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
		pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

		pSrc[2 * l] = xt;

		pSrc[2 * l + 1] = yt;

	} /* groups loop end */


#endif /* #if defined (ARM_MATH_DSP) */

}
